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Center for Functional Gastrointestinal and Motility Disorders and Division of Gastroenterology and Hepatology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.

BACKGROUND & AIMS:
Fiber supplements are frequently used as treatment for fecal incontinence (FI), but little is known about role of dietary fiber in the prevention of FI.

METHODS:
We performed a prospective study to examine the association between long-term dietary fiber intake and risk of FI among 58,330 older women (mean age 73) in the Nurses' Health Study who were free of FI in 2008. Energy-adjusted, long-term dietary fiber intake was determined using food frequency questionnaires starting in 1984 and updated through 2006. We defined incident FI as ≥1 liquid or solid FI episode/month during the past year during 4 years of follow up using self-administered, biennial questionnaires. We used Cox proportional hazards models to calculate multivariable-adjusted hazard ratios (HRs) and 95% CIs for FI according to fiber intake, adjusting for potential confounding factors.

RESULTS:
During 193,655 person-years of follow up, we documented 7056 incident cases of FI. Compared with women in the lowest quintile of fiber intake (13.5 g/day), women in the highest quintile (25 g/day) had an 18% reduction in risk of FI (multivariable HR, 0.82; 95% CI, 0.76-0.89). This reduction appeared to be greatest for risk of liquid stool FI, was 31% lower among women with the highest intake of fiber compared to women with the lowest intake (multivariable HR, 0.69; 95% CI, 0.62-0.75). Risk of FI was not significantly associated with fiber source.

CONCLUSIONS:
In an analysis of data from almost 60,000 older women in the Nurses' Health Study, we found higher long-term intake of dietary fiber to be associated with decreased risk of FI. Further studies are needed to determine the mechanisms that mediate this association.